noun
mirror go (as black)
A Go opening strategy where Black symmetrically copies White's moves, starting with the center point (tengen). Used as a psychological or experimental tactic.
太閤碁は、黒が天元に打ってから相手の手を真似る戦法だ。
Mirror go is a strategy where Black plays tengen and then mimics the opponent's moves.
天元 is the center point on the Go board; 太閤碁 starts with a move at tengen.
太閤 (Taikō, a title for Toyotomi Hideyoshi) + 碁 (go). The name likely references Hideyoshi's fondness for Go, but the exact origin of the term is uncertain.